1. Field of the Invention:
This invention relates to novel 16-membered macrolide antibiotic derivatives useful as antibacterial agents, and more specifically to 20-O-acyl-19,20-enolmacrolide antibiotic derivatives and their salts, which can achieve high levels in blood by oral administration.
2. Description of the Prior Art:
As 16-membered macrolide antibiotics, many derivatives, especially, below-described desmycosin derivatives having the general formula (I) in which a formyl group is bonded to the 19-position and O-mycaminosyl-tylonolide (OMT) derivatives have been synthesized and reported to date.
Although they show high antibacterial activities in vitro, they do not show sufficient effects in experiments for the treatment of infected animals by their oral administration. It has been indicated as a possible cause for the above drawback that the 19-formyl group would affect adversely on their absorption characteristics, thereby failing to achieve any high levels in blood. However, there have not been found to date any compounds which have overcome the aforementioned drawback.